Prenatal detection of mosaic trisomy 1q due to an unbalanced translocation in one fetus of a twin pregnancy following in vitro fertilization: A postzygotic error

Abstract

Complete or mosaic trisomy for all of chromosome 1q has been seen rarely in a recognized pregnancy. A patient presented with twins following in vitro fertilization (IVF). Ultrasound showed twin A to have a diaphragmatic hernia, thick nuchal fold, and subtle intracranial abnormalities. Twin B appeared normal and a thick dividing membrane was seen. Amniocentesis of twin A showed a male karyotype with mosaic trisomy 1q in 57% of cells resulting from a translocation between chromosomes Yq12 and 1q12. Parental karyotypes were normal. The twins were delivered at 33 weeks. Twin A died at 1 hr of life. Autopsy confirmed the left diaphragmatic hernia and hypoplastic lungs. Autopsy also revealed a partial cleft palate, syndactyly of the second and third toes bilaterally, external deviation of the left 5th toe, and contractures of the index fingers bilaterally. A recent report documented formation of a chimera resulting from embryo amalgamation after IVF. Given the rarity of the cytogenetic findings in our case, we sought to determine if the mosaicism was a result of chimera formation related to the IVF. Thirteen polymorphic loci throughout the genome, in addition to four on 1q and four on 1p, were amplified by PCR. Only two alleles were observed at each of these loci in twin A, one paternal and the other maternal. We present further clinical findings of this case with a rare cytogenetic abnormality that appears to have originated from a postzygotic mitotic error and not embryo amalgamation.

De novo copy number variants are associated with congenital diaphragmatic hernia

“…There are several previously reported CDH patients with duplication of 1q 39 40. Most of these duplications are the consequence of a balanced parental translocation.…”

Prenatal Diagnosis of Congenital Diaphragmatic Hernia in a Fetus with 46,XY/46,X,-Y,+der(Y)t(Y;1)(q12;q12) Mosaicism : A Case Report

“…Kaufman et al (24) described a fetus whose ultrasound at 19 weeks showed an absent calvarium, large omphalocele, possible proboscis, and a suggestion of a VSD and whose karyotype was 46,XY/46,X,-Y,+der(Y)t(Y;1)(q12:q11) (24). Zeng et al (25) presented a twin following in vitro fertilization at 31 weeks' gestation. The karyotype of twin A was normal, while the others' karyotype was 46,XY/46,X,-Y,+der(Y)t(Y;1)(q12;q12) with left diaphragmatic hernia, hypoplastic lungs, a partial cleft palate, camptodactyly, syndactyly, ventriculomegaly, and hypoplastic cerebellum.…”

A Rare Case of a Mosaic Unbalanced Translocation After Chorionic Villous Sampling

“…A 39-year-old G4P0121 at 13.1 weeks underwent CVS secondary to advanced maternal age. A transabdominal CVS was performed and yielded a mosaic unbalanced 1;20 translocation (46,XX,der(20)t(q12;p13) [16]/46,XX [4]; see Fig. 1), leading to trisomy of almost the entire long arm of chromosome 1 (1q) and partial monosomy 20p.…”